Projection apparatuses are employed in home, office, architectural lighting, and planetarium applications etc. Several projection apparatuses have been developed in the art. U.S. Pat. No. 7,004,588 to Sadler discloses a planetarium projector comprising a point light source having substantially symmetric light intensity and an apparent cross-section of less than about 2 mm which is capable of generating a beam of high-intensity light having a certain cone angle, an enclosure having opaque regions and transparent regions that correspond to locations of individual celestial stars, wherein the enclosure includes an inner surface and an outer surface, and a light dispersing lens assembly disposed within the enclosure. The projector also includes a portable point light source comprising a light source, a light collection element and a light conducting conduit suitable for use in providing high intensity light with a small cross-sectional area.
U.S. Pat. No. 5,082,447 to Hinkle discloses a star projection device formed from an opaque film sheet folded to form a six-sided, cubical enclosure, the film having transparent spots extending over its entire area representing star positions when projected onto a surrounding surface, and a small, point-like light source is positioned at the center of the enclosure for projecting light simultaneously through all of its six sides to produce a substantially 360 degrees horizon less projection of the stars onto surrounding surfaces. Nearby stars are represented by linear extensions from the transparent spots representing vectors corresponding to the magnified heliocentric parallax motion of the star.
U.S. Pat. No. 4,776,666 to Kuehn discloses an improved projector for projecting fixed stars in planetarium increasing the brightness and the brilliance of the projected sky by using fiber optical light guides. The device comprises at least one light source, one condenser, one star plate or templates and one lens, which projects the star plate template on the planetarium dome. A fiber optical light guide cable, the light-entry end of which faces the condenser and which consists of fiber optical light guides or fiber optical light guide bundles, is provided between the condenser and the associated star plate or template. The other end of the fiber optical light guide cable is split up into fiber optical light guides and/or fiber optical light guide bundles, the light-emergence ends of which are assigned to the locations on the star plate or template which are to be illuminated.